JPH0225290A - Consumable welding rod and usage thereof - Google Patents

Abstract

PURPOSE: To obtain a self-shielding and consumable electrode by making an electrode have compressed granular filling material and a concentric coating of metal containing iron which are used for the welding of steel having specific tensile strength and elongation, and making the filling material have specific concentration of Al, Ni, Mn and limiting C. CONSTITUTION: This is an electric arc welding electrode which has an outer coating of metal containing iron formed around a concentric core of compressed granular filling material which is used for depositing weld metal of a steel of multiple passes having a minimum elongation of about 22% and a minimum tensile strength of about 5040 kg/cm<2> . This filling material contains Al the weight of which is bigger than about 1.50% of the weight of a whole welding rod. This filling material has a combination of Ni and Mn in the range of 2.5-4.0 wt.% of a whole welding rod, and Ni is greater than about 0.5% and Mn is in the range of 0.7-2.0%. In the welding rod, the C in its filling material makes a weld metal, deposited when the coating and the core are melted and deposited, which has C of less than 0.12%. A self-shield and cored consumable electrode can be supplied by using filler of high Al content hereby.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the art of electric arc welding and further to improved welding rods and atmospheric electric arc welding methods using self-shielded consumable welding rods. . The present invention is particularly applicable to atmospheric arc welding using a bare tubular welding rod in which the flux material is contained inside the tube as a granular filling which together with the slag slack and shielding material produces an alloy metal. be. Such consumable welding rods are well known to those skilled in the art as self-shielded welding rods, whereby the filling material in a window surrounded by a tubular sheet metal in the form of low carbon steel produces alloying elements. , resulting in mechanical properties of the weld metal deposited by the welding rod as it melts in the arc welding process. The present invention relates to the composition of an alloy material within the granular filling of the core within the outer tubular covering of a welding rod, and it will be described with particular reference to it. The present invention may include other particulate materials of the core such as self-shielding cored consumable welding rods that produce a shielding effect. The basic slag system of conventional welding rods remains unchanged to produce the improved welding rods of the present invention.

[Conventional technology]

As information on the conventional technology, Barber Straw (H8!-
U.S. Pat. This is not a particularly improved electrode according to the invention.

[Summary of the invention]

In producing self-shielded, consumable, cored welding rods of the type used in multiple bath welding passes to form beads, the granular filler material eliminates the oxygen and It has been established by the inventors and is now well known that sufficient aluminum must be included to reduce the deleterious effects of nitrogen. By incorporating relatively large amounts of aluminum, welding rods can be easily used for.

This is because it is not affected by the cleanliness of the steel being welded and the welding process used. Weld beads have excellent appearance as well as great resistance to porosity. For 70 reasons, alloyed aluminum is added to the filler material so that aluminum accounts for 1.20% of the total weld metal deposit.
% total weld metal. However, such high aluminum content tends to prevent structural transformation of the weld deposit, thus forming large guffins that substantially reduce the ductility of the weld metal. In fact, aluminum reduces ductility and deposits brittle weld metal, which easily fractures. As a result, it is largely standard practice to add alloying carbon to the filler material to transform into a thin guffine ductile structure. Welding rods of the type to which the present invention relates therefore utilize a carbon-aluminum system, in which the aluminum increases to near the maximum possible extent, i.e. about 1.8% of the total weld metal, and the aluminum increases otherwise. The low ductility produced by the weld metal is avoided by increasing the carbon content of the total weld metal, typically to a level of 0.2 to 0.3 weight percent. Balancing aluminum and carbon produces weld metal deposits that are satisfactory from a ductility standpoint. In the art, the aluminum content in the filling material generally cannot exceed an upper limit value for two reasons. The limits of this aluminum-carbon system are controlled by the need for an acceptable level of ductility in the total weld metal, a property degraded by excessive levels of carbon and high tensile strength. Therefore, no satisfactory results with carbon-aluminum systems are usually obtained for aluminum contents greater than about 2.0% in the total weld metal. Beyond the ductility limitations of this type of alloy system, the American Welding Institute (AWfl) has set an upper limit of 168 thialuminum on the total weld metal deposit produced by this type of welding rod. This aluminum gold in the total weld metal deposit is returned by a generally corresponding amount of alloyed aluminum in the granular material forming the welding rod mass. Under equal conditions, there is a direct relationship between the aluminum of the core material and the aluminum of the total weld metal as a welding rod containing an iron or steel coating. The designation of aluminum has general applicability. About 2.0% aluminum by weight in the total weld rod generally yields about 1.6% aluminum by weight in the total weld metal. This same general ratio can be applied to other percentages of aluminum. A similar relationship can be applied to carbon in the aluminum-carbon system used in the welding rod material of the present invention.

The American Welding Society has specified requirements for various self-shielded consumable welding rods for multiple pass deposition of mild steel. One of the more common classifications of welding rods is
E70T-7, which is about 4200#/m” (
60,000 psi) minimum yield strength, approximately 50,408/cm (72,000 psi) minimum tensile strength and 22%
The amount of welding required that the welding rod produce weld deposits compatible with low elongation. This is a somewhat standard specification for welding rods of the type to which this invention relates. In order to produce welding rods that meet these requirements, aluminum and carbon systems have until now been used with appropriate levels of carbon, typically 0.24-0.28% of the total weld metal, to produce the desired ductility. but about 1.45% and preferably about 1.5% of the total weld metal.
Large amounts of aluminum above 0% but below about 1.8% have been adjusted in a manner that produces the desired benefits. The disadvantage of this granular type of self-shielding consumable cored welding rod is that as the carbon increases and becomes more ductile, the notch toughness becomes quite low (apparently due to the carbide at the grain boundaries). In addition, AWS specification E
The deposition rate of cored welding rods conventionally adapted to 70T-7 is relatively fast. At high deposition rates, substantial notch toughness of the total weld metal deposited is obtained due to the reduced refining of grains from subsequent passes forming a typical weld and the uniquely dense weld beads. is 4 more. Considering this situation, the AWS specification is E70
No special level of notch toughness is required for welding rods meeting the T-7 specification. As a result, E70T-7
The use of type welding rods has generally been traditionally limited to applications where a minimum notch toughness value is not a requirement.

The present invention relates to an improvement in a self-shielded cored consumable welding rod using a nitrogen scavenging system to an aluminum-based deoxidation ratio, which provides good ductility and a significant increase in notch toughness, i.e., chirpy V-notch scale. .

Approximately 484 clR-kg (approximately 35 ft-
tb) Obtaining the characteristics of a voltage range to a good resistance difference to the porosity of the welding rod containing a relatively large amount of aluminum in the window while achieving the above. In addition to obtaining the advantageous results of a cored welding rod that deposits steel in multiple passes with high aluminum content and a significant increase in notch toughness, the present invention also maintains fast deposition rates. The AWS most dog-left aluminum of the self-shielding system to which this invention relates is 1.8% of the total weld metal, which is not exceeded by the aluminum in the filler material reaching the maximum of 2.391 for welding rods containing metal cladding. . Therefore, high aluminum in the alloy system to which this invention is concerned results in an aluminum content in the total weld metal of aluminum of less than 1.1 EJ. In order to retain the high welding properties and other advantages of aluminum self-shielding systems, the alloy aluminum of the present invention is maintained at a novelty of more than about 1.50 inch of the total weld metal, so that the total weld metal It has at least about 1.20% aluminum.

Preferably, the aluminum in the filler material is such that it produces at least 1.50% aluminum in the deposited metal.

According to the present invention, the carbon-containing family in the alloy system can be replaced with the conventional carbon-containing family.
Aluminum-based (reduced from that used in alloy systems), and a combination of nickel and manganese are added to the granular filler material, which may have a detrimental effect on the notch toughness of the structure (total weld metal). In this way, a cored consumable welding rod without an external gas shield has the benefit of a high aluminum content while having increased notch toughness. This result could not be obtained for many years in high-aluminum self-shielding systems that produce steel deposits in multiple passes. By reducing carbon in the alloy system, carbide formation at the dalein boundary obviously reduced, it increases the notch toughness.

According to the invention, alloying carbon in the filler material is generally reduced to a minimum. By reducing the carbon in the alloy part of the filler material, the total weld metal has a carbon content of less than 0.12% and preferably less than 0.10%.

The present invention is an improvement in a self-shielded welding rod in which the carbon content in the alloy system of the granular filler is reduced so that the carbon in the metal coating is dominated by the carbon in the welding rod that alloys the weld metal.

A combination of nickel and manganese is added to the alloy system of the filler material to yield a combination of nickel and manganese in the range of about 2.5 to 4.0]iJ1% of the welding rod, where Nickel is greater than about 0.5% by weight of the welding rod and manganese is in the range of 0.7-2.0% by weight of the welding rod. The carbon in the filler material is usually less than 0.05%;
It is the removal of carbon in the filler material itself that is king.

By producing a welding rod with this alloy system for the filler material, the total weld metal deposited has an aluminum content of greater than 1.20% by weight and preferably greater than 1.50%, and about 0.12% by weight of aluminum. It has a carbon content of less than 0,000% by weight and preferably less than about 0,000%.

The use of combined nickel and manganese components in the filler material alloy system & a noticeable increase in ductility as well as weld metal notches hitherto not obtainable by high carbon content in the filler material of conventional welding rods. Produces toughness. This is an improvement over conventional self-shielded cored welding rods of this type.

A primary object of the present invention is to provide at least about 4
Provides a self-shielded cored consumable electrode utilizing a filler material having a high aluminum content alloy system that produces a weld deposit with a charred notch toughness of 84 cWL-4 (approximately 35 ft/lb) It's about doing.

Another object of the invention is to provide a multiple pass welding method with a welding rod of the type described above.

The improved welding rod of the present invention has substantial operator appeal and operational characteristics that make it useful for architectural welding of a variety of plate thicknesses. The welding rod has good penetration, good bead shape, good slag removal and shiny bead surface, which make it a good choice for many arc welding applications. The improved welding rod is AWSE70
Similar in operation to the T-7fll contact rod, but it is based on a carbon-aluminum alloy system in the filling material (
This type of welding rod differs from conventional welding rods by producing a weld metal with impact properties that could not be obtained with conventional metallurgy. In such systems, metallic aluminum is a major advantageous component and is used in the welding rod to improve the self-efficiency of the welding rod by providing a scavenger for nitrogen and oxygen in the arc and welding paradle. Develop shield properties. Welding rods of the present invention that contain large amounts of aluminum tend to have a larger voltage range, better operating characteristics and better bead shape and bead appearance. The present invention retains the good operating properties of conventional carbon-aluminum alloy systems due to the greatly reduced carbon content. Not only is moderate chirpy Y-notch properties achieved with the present invention, along with yield strength levels similar to conventional carbon-aluminum alloy systems, but as an additional advantage, the present invention provides Approximately 1.
It produces a greater elongation in the tensile test sample of 28 cm (0,505").

The present invention relates to a unique alloy system that is introduced via a filler material into welding rods of the type to which the present invention relates. In the past, the weld deposit aluminum content of self-shielded 7 lux cored welding rods intended to produce good notch toughness was generally less than 1.20%. By using the present invention, up to 2.01% aluminum in the total weld metal is used to improve arc travel and bead shape, reduce spatter, and produce a wide voltage range while welding beads. Improves resistance to porosity.

〔Example〕

Several welding rods according to the present invention were formulated as shown in Example I, Example I and Example II.

Example! A consumable welding rod was fabricated using a mild steel sheath around a core of compressed granular filler material, with the filler being 18.5 inches of the total rod weight and the sheath remaining. Coating 41 The carbon content of the coating is about 0.05% and the carbon content of the coating is about 0.05%.
It had a manganese content of 35% and the filling material was as follows:

Manganese metal powder Iron powder Song Aluminum metal powder Nickel metal powder Flux and shielding components 5.50 1.02 37.00 6.85 11.00 2.04 8.10 1.50 38.40 7.10 This welding The bar was formed into a consumable rod approximately 4 inches in diameter and multiple pass butt welded into a flat piece of flat carbon steel approximately 1.9 inches thick. The welding parameters used were: wire feed rate of approximately 381 m (150 inches) per minute, 325 amperes, negative DC welding rod, 25 arc volts,
The electrical stickout was about 3.8 steel (1% inch) and the interpass temperature was about 300°F. The deposition rate was approximately 5.184 (approximately 11.4 bonds) per hour.

The mechanical properties and chemical deposition chemical analysis of the total weld metal obtained from this test were as follows.

Yield strength: Approximately 4.865#/cm2 (69,500ps
i) Tensile strength: approx. 5,929 #/foil” (84,7
00pai) Chi elongation: 26 chia P V notch impact strength: approx. 635cpn-Jc9
C46ft・lb) Fruit [0°C (32°F)) Approximately 428cmkg (31ft-16) [-17.8°C (0°F)] Chemical analysis of sediment: 0.088% Carbon 1.33%
Manganese 0.09% Silicon 1.63% Aluminum 1.41% Nickel Example ■ The consumable welding rod of Example ■ was changed as follows.

Manganese metal powder Manganese iron oxide powder Aluminum metal powder bed Nickel metal powder Flux and shield component filling 3.40 4.05 11.30 8.10 38.05 Welding rod arrogance 0.68 0.81 7.02 2.26 1.62 7.61 Filling material t'3 of the welding rod in Example 20 of the total welding rod weight
．． 0 and the coating remained.

Using the test method of Example 1, the following total weld metal mechanical properties and deposit chemical analyzes were obtained for the Example Country consumable welding rods.

Yield strength: approx. 5.047 #/m” (72,1001
a4) Tensile strength: Approximately 6,013 Jtl/an” (85
, 9001ai) Chi elongation = 28% Charted notch impact strength: approx. 593.4c
3ft・lb) [0℃ (32°F)) Approximately 331c1n-kg (24ft-lb) [Approx. -6,6
7°C (-20'F) Chemical analysis of sediment: 0.079% carbon 1.47%
Manganese 0.16% Silicon 1.55% Aluminum 1.60cm Nickel Example 〼Example ■The consumable OOT capable welding rod in Example ■ was changed to 5 as shown below (1) Fi-formed Ramangan 4.0
5 0.84 (2) Iron powder 3
8.50 7.97 (3) Aluminum metal powder
11.30 2.34 (4) Nickel metal powder 8.10 1.68 (5
) Flux and shielding components 38.05 7
．． The filler material in the welding rod of Example 88 was 20.7 inches of the total rod weight and the coating was the remainder.

Using the test method of Example I, the following total weld metal mechanical properties and deposit chemical analyzes were obtained for the consumable welding rod of Example II.

Yield strength 2 approximately 4,452H/cm2 (63,6001s
i) Approximately 5,488 kl/an” (78,4001a
t) Chi elongation 224% Char 2-v notch impact strength: Approx. 704c1n・kg (
51/iJ [0°C (32°F)) Approx. 4691・klc34ft-16> (-17.8°C (0°F)) Chemical analysis of sediment: 0.082% Carbon 0.98%
Manganese: 0.16% Silicon: 1.76% Aluminum: 1.63% Nickel From these three examples and other tests, nickel is greater than 0.5% by weight of the welding rod and manganese is greater than 0.7% by weight of the welding rod. 2.0 weight'! ! When using a granular filler material formulated to produce a welding rod alloy system in which the combination of nickel and manganese is within the range of 2.5% to 4.0% by weight of the welding rod. , and the AWS tensile and elongation requirements for E70T-7 welding rods at 0°C (32°F) when carbon in the welding rod is limited so that the total weld metal carbon does not exceed 0.12% by weight. Approximately 483ctn-4
(ft-16) with a charvy Y-notch toughness exceeding 16 ft-16.

The preferred ranges of operable elements in the total weld metal using the present invention are as follows.

All welded metal ((1) Carbon 0.06-0.1kg
(&) Manganese 1.0~1.5 (1
) Aluminum 1.40-1.75(d)
Nickel 1.4-2.0%, residues of other metals e.g. max. 0.02 phosphorus and max. 0.01
of sulfur is also present in the weld deposits. This is because they exit from the steel surrounding the system along with the reducible compounds that make up the slag system.

In embodiments, the manganese is partially obtained from manganese oxide in the filler material, which is readily available in powder form.

In theory, nickel and manganese are included in any form reducible by the aluminum to produce elemental nickel and manganese for alloying in the weld metal. According to the invention, the carbon in the welding rod, filler material and coating of the steel is controlled such that the carbon content of the total weld metal deposit does not exceed 0.12% by weight of the total weld metal and preferably 0.12% by weight of the total weld metal. 10] Less than ii. Aluminum 9 in filling material
The load is provided by powdered aluminum, with a welding rod of 1.50 iJl and a welding rod of 2.5 iJl.
Present in less than % by weight. In this manner, the total weld metal contains aluminum in the general range of 1.23 to 2.0% by weight of the total weld metal.

According to another aspect of the invention, an atmospheric (i.e. without external gas shield) electric arc by single or multiple passes of a self-shielded consumable cored welding rod of the type made according to the invention. A method of bathing is provided. At least approximately 641 cm/kg per turn of this welding rod at 0°C (32°F)
(35/l-16) yields a deposition rate in excess of about 4.54 kg (about 10 bonds) per hour along with a chirvine notch toughness of (35/l-16). This method requires at least about 0.06 mm of welding rod
A process of providing a coating of steel with a carbon content of 1 by weight, filling material in the coating (as a welding rod alloy system, 2.5 of the welding rod
Provide a combination of nickel and manganese ranging from ~4.0wt%, with nickel greater than 0.5wt% of the welding rod and manganese ranging from 0.7 to 2.0wt% of the welding rod. ). The aluminum alloy of the present invention has a carbon content of more than about 1.50% of the total welding rod, including the coating and filler materials.
Less than about 0.15% by weight of the welding rod, so the total weld metal deposited is about 1.5% by weight when the welding rod is melted and deposited.
2% by weight of aluminum alloy as well as about 0.12
The weight of the carbon alloy is less than 1%. The method includes passing an electric current through a countersunk welding rod to create an electric arc for melting the coating and core material, and at least 1.2
The process involves depositing the welding rod metal onto the blank as a total weld metal having 0% aluminum and less than or equal to 0.12i of carbon. By using this method, approximately 4
．． Deposition rates substantially higher than s6 kg (10 bonds) were obtained with multiple pass welding, while AWsE70T-7
while maintaining compliance with the strength and ductility requirements of
Chirpy V-notch toughness in excess of about 484 a+s·kg (35 ft·lb) at 2°F).

The filler material includes alloy, flux and shield components, the first of which is modified according to the present invention. When considering the example, it is found that the filling contains iron powder, which the procedural amendment forms another source of iron for the weldment, and the aforementioned three types February 10, 1999

Claims (17)

[Claims] (1) Minimum elongation of approximately 22% and approximately 5040 kg/cm^
An outer layer formed around a generally concentric core of compressed granular filler material used to deposit all weld metal in multiple pass steels having a minimum tensile strength of 2 (approximately 72,000 psi) in a self-shielded consumable electric arc welding rod having a coating of a ferrous metal, the filler material comprising aluminum in an amount greater than about 1.50% of the weight of the total welding rod; Welding rod 2.5~
having a combination of nickel and manganese content in the range of 4.0% by weight, the nickel being greater than about 0.5%, the manganese being in the range of 0.7-2.0%, and the loading The carbon in the material is limited so that when the coating and core are melted and deposited, all weld metal deposited is 0.
A welding rod having a weight percentage of carbon of 12% or less. 2. The nickel in the granular filler material is at least partially in the form of NiX, where X is one or more elements reducible by aluminum in an electric arc. A consumable welding rod with an improved core. 3. The manganese in the granular fill material is at least partially in the form of MnX, where X is one or more elements reducible by aluminum in an electric arc. A consumable welding rod with an improved core. (4) The Cha of all the above weld metals
claim 3, wherein the V-notch toughness is at least about 484 cm kg (35 ft·lb) at 0°C (32°F).
A consumable welding rod having an improved core as described. 5. The improved core consumable welding rod of claim 4, wherein said aluminum in said filler material is greater than 1.50% and less than about 2.5% of the total welding rod weight. 6. The improvement of claim 5, wherein said carbon of said coating and filler material is included in an amount selected to result in a total weld material having a carbon content of less than 0.12% by weight of the total weld metal. A consumable welding rod with a solid core. 7. The improved core consumable welding rod of claim 6, wherein said carbon comprises less than 0.10% by weight of total weld metal. 8. The manganese of the particulate filler material is at least partially in the form of MnX, where X is one or more elements reducible by aluminum in an electric arc. A consumable welding rod with an improved core. (9) The chirp V-notch toughness of all said weld metals is at least about 484 cm·kg (484 cm·kg) at 0°C (32°F).
9. The improved core consumable welding rod of claim 8, wherein the welding rod is 35 ft.lb. (10) said chirp V-notch toughness of said total weld metal is at least about 484 cm·kg at 0°C (32°F);
(35 ft.lb). A consumable welding rod with an improved core according to claim 2. (11) The chirp V-notch toughness of all of the weld metal is at least about 484 cm·kg at 0°C (32°F).
(35 ft.lb). A consumable welding rod with an improved core according to claim 1. 12. The improved core consumable welding rod of claim 8, wherein the aluminum in the filler material is greater than 1.50% and less than about 2.5% by weight of the total welding rod. (13) The aluminum in the filling material is 1 of the total welding rod.
．． 3. A consumable welding rod having an improved core as claimed in claim 2, greater than 50% by weight and less than about 2.5% by weight. 14. The improved core consumable welding rod of claim 1, wherein the aluminum in the filler material is greater than 1.50% and less than about 2.5% by weight of the total welding rod. 15. The improved method of claim 8, wherein said carbon of said coating and filler material is included in an amount selected to provide a total welding material having a carbon content of no more than 0.12% by weight of the total welding material. A consumable welding rod with a solid core. 16. The improvement of claim 2, wherein said carbon of said coating and filler material is included in an amount selected to provide a total welding material having a carbon content of less than 0.12% by weight of the total welding material. A consumable welding rod with a solid core. (17) At least about 484 cm・k at 0°C (32°F)
Approximately 4.54k/hr with notch toughness of g (35ft・lb)
A method of performing electric arc welding in air by multiple passes of a welding rod having a self-shielded consumable core at a deposition rate in excess of 10 lbs. (b) providing a filler material in the coating producing a combination of nickel and manganese with a content ranging from 2.5 to 4.0% by weight of the total welding rod; providing, the nickel is greater than about 0.5%;
the manganese is in the range of 0.7-2.0% and the carbon in the welding rod is included in an amount selected to result in a total weld metal having a carbon content of 0.12% by weight or less;
Furthermore, the aluminum in the filling material is about 1% of the total welding rod.
．． (c) passing a current through the welding rod to create an electric arc to melt the coating and core material; and at least 1.20% aluminum and about 0.12% by weight; % of the total weld metal having less than % carbon on the blank.